Cool! Thank you! I tried to plot as well derivative of complex using following code: Plot[{Evaluate[complex[r, K1, K2, K3, P0]], Hold[Evaluate@D[complex[r, K1, K2, K3, P0], r]]} // Release, {r, 0.1, 6}] without success. I'm still a newbie in mathematica, so I will be happy if you help me one more time.
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user4545Nov 9 '12 at 18:45

@Philipp Here comes the help for one more time! I updated the answer to accommodate derivatives with in the definition of complex. You need to change the definition of the function itself. You cant perform the D[] inside Plot as complexwas previously defined not be symbolic but only numeric inside Plot.
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PlatoManiacNov 9 '12 at 20:23

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